Compressed gas contained in a gas cartridge, for example a single-use gas cartridge, is often employed as a reliable and quick source of energy in diverse fields including emergency inflating devices, cooking tools and paintball guns. These disposable cartridges are usually sealed with a clamped membrane from which gas is released by puncturing the membrane. Some applications may require high power density which involves gas pressures that may exceed a hundred times the atmospheric pressure. Thereby, for security and handling reasons, the membrane is made strong enough to prevent any unintended gas release and is therefore hard to puncture manually without a certain level of mechanical advantage.
With each new application of these cartridges may come a new technique to force a puncturing member, for example a punch through the membrane, or to force the membrane onto the puncturing member to release the gas. As a result many solutions currently exist from which designers may pick from to ease the use of these cartridges in their respective devices. Frequently encountered mechanisms use a lever or a screw to produce the required mechanical advantage allowing a user to pierce the cartridge membrane with its lone hand strength. Other designs rely on energy stored, for example, by means of a pre-compressed spring, in which the energy is released by the user with minimal force for pushing the puncturing member against the cartridge membrane or for pushing the membrane onto the puncturing member. A frequent problem resulting from the use of a pre-compressed spring is that components that maintain the spring in a compressed position may gradually suffer from plastic deformation, reducing an amount of energy stored in the spring. For some applications, use of a pre-compressed spring may also be dangerous because of possible unintended release of the energy storing mechanism, due to a shock or to mishandling.
Earlier solutions may not be adequate depending on constraints inherent to some applications. Also, design constrains may be of several kinds including device's final size, cost, fabrication process, storage duration and conditions, final usage and so on.
Some earlier pressurized gas cartridge concepts reduce the necessary force to break the seal and release the gas. A gas cartridge proposed in U.S. Pat. No. 6,047,885, issued Apr. 11, 2000, features an elongated stem attached to a closure member of the gas cartridge that, when pushed sideways, allows to easily break the seal with a minimal lateral force. This type of gas cartridge is difficult to manufacture and is prone to gas leaks. Moreover, a minimal amount of force is required to break its seal, which may accidentally be broken, so the gas cartridge must be handled with great care. This solution additionally requires use of a specially designed gas cartridge and is thus not suitable for use with standard gas cartridges.
Another pressurized gas cartridge is disclosed in U.S. Pat. No. 7,156,257, issued Jan. 2, 2007. The gas cartridge features a clamped membrane which, instead of being flat, is concave and has a bump toward the inside of the cartridge. The shape of this membrane allows the use of a thinner membrane, compared to a conventional flat membrane design. Use of this thinner membrane to safely and effectively seal the pressurized gas cartridge should make the membrane easier to break. Additionally, this recessed membrane design does not suffer from any transportation or handling issues. However, there remains a problem of reducing the required force for puncturing a curved membrane. The design is also expected to involve increases in manufacturing complexity and in associated cost. Finally, this solution is not suitable for use with standard gas cartridges.
Introducing a new type of gas cartridge would, for some applications, require approval by regulating institutional bodies related to the transportation industry, to healthcare services, to the protection of the environment, and the like. Obtaining regulatory approval for a new type of gas cartridge could lead to development delays and cost increase.
Therefore, there is a need for an improved technique for puncturing pressurized gas cartridges.